The present invention relates to a method and system for controlling smoke emissions in a engine and specifically controlling spray plume characteristics.
Engine emissions control is very important in today""s environmentally conscience society. Regulations have continually reduced the amount of allowable emissions, forcing engine manufacturers to find new ways of controlling the combustion process.
One area that has received considerable attention is the fuel injection process and its impact on combustion. A fuel injector injects pressurized fuel into the cylinder. In order to optimize the combustion process, it is desirable to atomize the fuel as much as possible, thereby reducing emissions. In order to properly atomize the fuel, it is necessary to expose the spray plume to as much area (combustion air) as possible; however control of plume size is necessary. If the spray plume is too large, such that the spray contacts the cylinder walls or piston, combustion is negatively affected and emissions are increased. Further, if the spray is too small, insufficient atomization can not occur, thereby preventing complete combustion and increasing emissions.
The prior art has attempted to control emissions related to fuel injection with timing, injector angles, swirl chambers, and other fixed designs. However, these approaches do not address the fact that the conditions affecting spray plume characteristics, such as length and angle, change with operating conditions. For example, the parameters that exist during cold start are noticeably different from the parameters that exist during hot running. The present invention is directed to overcoming one or more of the problems identified above.
The present invention provides a method and system of reducing emissions from an engine. The method comprises determining spray plume parameters, calculating fuel injection spray plume characteristics, comparing the spray plume characteristics to predetermined spray plume characteristics and adjusting at least one fuel injection characteristic in response to the comparison in order to change the spray plume characteristics closer to the predetermined spray plume characteristics. The system includes a combustion chamber, a fuel injector, means to determine spray plume parameters, and an electronic control module to calculate and adjust spray plume characteristics.